Large scaling and high integration of a semiconductor device are in progress. A micro-machining technology supports the progress. In the micro-machining technology, a lithography technology can be advanced by reducing a wavelength of a projection exposure device or by increasing NA of a projection lens. However, such a lithography technology has encountered limitations, and, in a method using ultraviolet light or far-ultraviolet light, a substantially 40 nm half pitch is a limit. As a method of surpassing the limit, a method using EUV light has been developed. However, the developed method has not been commercialized. Meanwhile, pattern forming methods of using various processing technologies, or new methods of using characteristics of the material have been developed.
As one method among the above-described methods, the Self aligned double patterning (SADP) method (NPL 1) of doubling a pattern by self-aligning or the Self aligned quadruple patterning (SAQP) method of quadrupling a pattern by the self-aligning is provided. In such a method, a material having high etching-resistance selectively remains on a side wall of a pattern formed by lithography, the pattern formed by the lithography is removed, and thereby the remaining side wall is used as a pattern. Accordingly, it is possible to double a pattern. If this step is repeated twice, it is also possible to quadruple a pattern. In other words, it is possible to reduce a pitch in a pattern to be ½ or ¼.
As a method of causing the number of patterns using characteristics of a material to be increased to be n times, a method of using a self-derivative assembly process, that is, Directed Self Assembly (DSA) (NPL 2) is provided. The method is a method of using the principle in which self-assembly is performed with a difference of thermodynamic characteristics between two types of polymers, by using a material in which the two types of polymers referred to as high-molecular block copolymer are synthesized to each other, so as to perform block binding. With this method, a plurality of patterns can be formed on the inner side of a pattern (guide pattern) formed by lithography, or fine holes can be formed on the inner side of a hole having a large size, by self-alignment.
PTL 1 discloses that a plurality of reference lines is superimposed on a contour line image obtained based on a scanning electron microscope image of a photomask, and measurement is performed by using the reference lines.